If one wants to be an Nutritional Therapist then he/she have to complete his education with PG in Nutrition and Dietetics.

At IGNOU for the course of Nutrition and Dietetics, the eligibility criteria is:

B.Sc Home Science with specialization in Food and Nutrition, Dietetics and Clinical Nutrition
Or
PG Diploma in Dietetics and Public Health Nutrition or its equivalent
Or
Graduate (B.Sc. Hons.) or equivalent (MBBS, BHS etc.) from any of the following backgrounds: Home Science/ Food Science and Technology, Zoology, Microbiology, Biochemistry, Pharmaceutical along with the DNHE or CNCC or CFN offered by IGNOU. (Simultaneous admission for CFN/CNCC also permitted).

So if you are Food Technologist then yeah! you are eligible for the course of MSc Nutrition and Dietetics and you can become Nutritional Therapist.

To know more about the Nutrition & Dietetics, visit the link below:

https://www.careers360.com/articles/4880-Career-review-nutrition-and-dietetics

I hope this answer helps. All the very best for your future endeavors!